Cutting a giant hole in my bass drum's shell

Jankowske

Senior Member
So I've seen bass drums that that already have a big ol' vent, but I have yet to see any information on someone doing it themselves to a perfectly good bass drum. I dig those Kumu drums, and I saw an old picture posted by Bermuda with a more oblong hole-thing, but yeah. Nothing on how to do-it-yourself so far.

But WHY would I want to do such a thing, you ask? Here's my reasoning. This piece of junk kickport thing I have actually works with my kick, sort of. It's cool and all that it does all that tasty sub-bass stuff, but what's not so cool is how much it weighs and that it needs to be attached to my reso head. As if a giant hole in the head doesn't mess it up enough, then wedge a heavy chunk of plastic in there. And I liked my fiberskyn head before I cut a big hole in it. I liked it less so after I cut the big hole in it.

Also I tend to bury the beater most of the time and I have little love for rebound, so I prefer the feel of a vented bass. And a big hole is handy for pillows and mics and whatever else I need to reach in there for. So here I am wanting an intact reso and a big hole.

I'm thinking that a kickport would work the same way mounted on the shell as it would on the drumhead. Probably better. And I know that drilling shells is anathema to most, but I think that a nice, rigid, medium-thickness maple shell would suffer less from a 5" hole than a flimsy mylar diaphragm meant to be under even tension. I'd probably have to soften up the kickport with a heat gun or something to get the flange to conform to the radius of the drum, since I'm pretty sure it needs some sort of baffle to work. And I could do away with the horrible rubber foreskin and foam gasket by securing it with silicone caulk. I plan on doing this somewhere mid-shell, maybe closer to the reso, and somewhere between the side and the bottom of the shell so that it's sort of pointing towards the floor. Something about bass reflection makes me think it'd be more efficient there.

So has anyone else done this? At least the hole-cutting part? Because that's what I'm stuck on. I think my biggest hole saw is like 4". I'm not too bad freehanding with a router, though. Also, the only other thing really hanging me up is that I really, really like my drums, and busting a giant hole in the most expensive one sounds a little sketchy even to me. I do have another kick or two to try it out on, but they have different dimensions, so I'm not sure how helpful it would be to destroy them as well.

Any ideas/advice/vehement discouragement is welcome. Thanks!
 

larryace

"Uncle Larry"
You're a brave man. I would experiment on a cheap set first. A 4" hole seems like it would do the trick. I don't see the need for a bigger hole. Me, I'd make it so you could close it up again. Like if you could somehow thread a a round perfectly sized piece of wood that matches your finish in the hole to allow it to close up so you aren't stuck with one option. Trying to re-use the slug would be ideal, but it would be too small to thread in. You'd have to tweak it or the shell so it would fit
 

Les Ismore

Platinum Member
We eagerly await the results.

If you hear a difference in one kick, its sure to be the case with other drums.
 

mmulcahy1

Platinum Member
So Jankowske, I guess you're the guinea pig on this one.

If you actually do it, record your bass for before and after comparisons.

Plus pictures!!
 

Les Ismore

Platinum Member
So Jankowske, I guess you're the guinea pig on this one.

If you actually do it, record your bass for before and after comparisons.

Plus pictures!!

Video the cutting of the hole if you can, that'd be great entertainment.

In theory it should work, don't know if the KICKPORT apparatus is the desired piece of porting material tho, a drum shell has a curve, not flat like a head. There's always silicone and PVC tubing.
 

caddywumpus

Platinum Member
+1 for "you're the guinea pig"

I'm interested in the idea of the hole being on the bottom for bass reflex purposes. My friend has an Acoustic Image bass combo amp, and the woofer is pointed towards the floor, and it supposedly translates the bass frequencies better that way. I'm curious how a Kickport would possibly work in this instance.
 

Les Ismore

Platinum Member
The ultimate would be an adjustable port, so you can tune the bass drum to the room/space you're in. It could be a telescoping tube affair. Of course there'd be a supplied corking type of plug for those rare instances where you'd want no port.

And there's another idea! A plug type accessory for ported kick heads.

Lightweight removable plug/patch for all the Joe's who have a hole cut in their BD head, the best of both worlds could then be attainable... hopefully for under $20
 

bermuda

Drummerworld Pro Drummer - Administrator
Staff member
IF the Kickport has any bass-enhancing properties, it would work as well on the shell as on the head, and without robbing the head of its resonance. Also - and this was part of my idea in porting the shell in the first place - any artwork on the front head could remain complete... no hole. :)

If I was cutting a round hole in a shell, I would get round metal disc in the size of the hole I want, and screw it into the shell in the desired hole placement (use 2 opposing screws so the disc doesn't rotate out of position.) Invest in a RotoZip, which is part drill, part jigsaw, in that it uses a standard looking drill bit, but cuts sideways and in smooth curves (which is tough with a jigsaw.)

Drill a hole in the shell right on the edge of the metal guide disc, insert the RotoZip bit, turn on, and follow the perimeter of the disc. If you go slowly and follow the disc, you will have a lovely circle when you're done! I suppose that would work for any shape as well.

Well, that's what I'd do anyway. :)

Bermuda
 

Michael Madio

Pioneer Member
Don't forget that a big portion of the KickPort's sound is the mass it adds to the reso head ... you won't get that dampening when the KickPort is mounted in the shell.
 

GruntersDad

Administrator - Mayor
Staff member
The drum shell is curved. The batter head is flat. Is the Kickport going to sit flush in the shell knowing that it won't be sitting on a flat surface. and the curvture of the shell is going to give the circle cut in it an oblong shape.
 

bermuda

Drummerworld Pro Drummer - Administrator
Staff member
My understanding of the Kickport is that it's "reflex" design accentuates/enhances the fundamental frequencies (a la the small Bose stereos, and Klipsch folded bass cabinets.) As far as damping the head, that can be accomplished - if desired - in other ways, and variable as needed. In a recent Kickport thread, it seems like the biggest complaint was that it damped the head too much.

There is one problem with altering the shell: it will probably hurt the resale value.

Bermuda
 

KamaK

Platinum Member
I don't want to discourage you. This isn't going to work in the manner in which you think it's going to work. I highly recommend doing this to horrible-quality BD before you cut a hole in something you might regret.

If anything, you far more likely to produce something visually interesting than an improvement in the sonic quality of the BD.
 

porter

Platinum Member
I've thought about doing this before, or doing it to a different kit, but never went through with it. I do have a drill press & hole saws, which I imagine would do the cutting quite well. I know I'm very interested in what kind of result you'd get, since I also prefer a full reso but not the feel (and my 2" port right now gives me no room to adjust anything inside the drum.

Please, let us know if you do do it.
 

bermuda

Drummerworld Pro Drummer - Administrator
Staff member
The drum shell is curved. The batter head is flat. Is the Kickport going to sit flush in the shell knowing that it won't be sitting on a flat surface. and the curvture of the shell is going to give the circle cut in it an oblong shape.
As long as the Kickport is a good fit with a suitable 'gasket', any hole variation won't be visible and should affect the performance.

To assure a more perfect circle, if the metal guide is slightly bent to follow the drum's curve, it should work fine.

Bermuda
 

Jankowske

Senior Member
Wow, thanks for all the replies already.

To larryace: the i.d. of the kickport is 4", and I dig the amount of rebound I get with that. Then again I think I remember someone saying that less air is displaced via a shell vent than would be for an equally-sized head vent...something about the air column of the drum's volume and the way the batter head moves it...idk. Anyways it would effectively be a 4" hole, and possibly "feel" smaller. And I've thought of a plug/patch, too, but I'm still thinking on just how to do it. Hopefully my results won't make me want to instantly reverse my operation. =P

mmulcahy1: I'll try, but I'm not sure how "objective" the recordings would be. If I do go through with this I plan on getting a new bass reso, and this time I think I'll go for a diplomat fiberskyn instead of an ambassador. Small change but still another variable. Plus it will sound drastically different just from being intact. But I'll try to get some decent clips.

GRUNTERSDAD: Not sure if I made it clear before. Once the hole is cut, I plan to soften up the kickport and kinda mold the edges of its bell/flange thing to the radius of the drum. Afterwards It wouldn't even work on a head since the "back" of it would be curved. This seems kinda messy and this scheme's kinda silly enough already to potentialy ruin a ~$300 drum for the sake of a $40 piece of plastic...but I try not to think about that too much. Progress and whatnot.

Les Ismore: I was thinking of that too. I'm sure the kickport could be greatly optimized by altering its length. I recall reading that it was supposed to work best with 20" kicks. I would guess that it would work better with my 22x18" if length was added. Some cheap 4" cardboard tube cut into rings of varying length could be experimented with, I suppose, to be slipped in/on the port's back. Or I could always just make my own port out of carddboard or something and forget the kickport entirely. The trick would be getting that nice flange/roundover to minimize chuffing and maximize dispersion.

bermuda: +1 on the bass drum art. I don't really dig the look of the kickport that much, either. Also I think my dad has something similar to the tool you described, but for sheet metal. Cool idea. I might just go with a hole saw if I can find a suitable size. I just found a 4 1/8" and a 5 1/2" hole saw in the basement; I have yet to check the garage to see if there's more. If I remember correctly, 5 1/4" is just right for a kickport, but 5 1/2" should work. Also I'm not worried too much about resale value. I plan to beat these 'til they fall apart.

And I don't know why I didn't already say this, but if anyone cares, my kit is a PDP X7 (the maple one) in pearlescent black. You get that nice dark tone when everything's black. ;) And right now I've got an (old) SKII on the batter with that black evans eq patch thing, and a fiberskyn powerstroke ambassador on the front. 22x18" shell, and I use the plastic side of the beaters on my custom 9000s. So it's definitely not a top of the line kit, but that's not gonna stop me from crying and resorting to self-flagellation if this all goes horribly awry. I think I'll definitely test this on my "other" kit first.

Another thing that worries me that no one's touched on yet is shell deformation over time and how hole placement might affect this. I know those Kumu's are pretty thin-shelled and none too stingy with their hole diameter, but there shouldn't be too much stress on the middle of the shell, right?

Thanks again for the interest.
 

KamaK

Platinum Member
Les Ismore: I was thinking of that too. I'm sure the kickport could be greatly optimized by altering its length. I recall reading that it was supposed to work best with 20" kicks. I would guess that it would work better with my 22x18" if length was added. Some cheap 4" cardboard tube cut into rings of varying length could be experimented with, I suppose, to be slipped in/on the port's back. Or I could always just make my own port out of carddboard or something and forget the kickport entirely. The trick would be getting that nice flange/roundover to minimize chuffing and maximize dispersion.
Since the kick port is no more than a single-flanged tuned port, I would recommend that you do the arithmetic and purchase a rigid flanged port from a DIY Speaker-building site so you can tune it to a frequency appropriate to your kick.

I 'think' you can even find telescopic ports, which allow you to adjust the tuning after installation.
 

larryace

"Uncle Larry"
There's a member here that goes by the name of Wavelength. He owns Kumu drums. You could PM him and get his take on the whole shell port thing. He's had them for some time now.
 

Hollywood Jim

Platinum Member
Another thing that worries me that no one's touched on yet is shell deformation over time and how hole placement might affect this. I know those Kumu's are pretty thin-shelled and none too stingy with their hole diameter, but there shouldn't be too much stress on the middle of the shell, right?

Jankowske:

I love this idea you have. I think it will work great.




As far as stress in the middle of the bass drum shell, normally I don't think there is any.....................





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